On Wed, Feb 19, 2025, Yosry Ahmed wrote: > Instead of using X86_FEATURE_USE_IBPB to guard the IBPB execution in the > vCPU load path, introduce a static branch, similar to switch_mm_*_ibpb. > > This makes it obvious in spectre_v2_user_select_mitigation() what > exactly is being toggled, instead of the unclear X86_FEATURE_USE_IBPB > (which will be shortly removed). It also provides more fine-grained > control, making it simpler to change/add paths that control the IBPB in > the vCPU load path without affecting other IBPBs. > > Signed-off-by: Yosry Ahmed <yosry.ahmed@xxxxxxxxx> > --- > arch/x86/include/asm/nospec-branch.h | 2 ++ > arch/x86/kernel/cpu/bugs.c | 5 +++++ > arch/x86/kvm/svm/svm.c | 2 +- > arch/x86/kvm/vmx/vmx.c | 2 +- > 4 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h > index 7cbb76a2434b9..a22836c5fb338 100644 > --- a/arch/x86/include/asm/nospec-branch.h > +++ b/arch/x86/include/asm/nospec-branch.h > @@ -552,6 +552,8 @@ DECLARE_STATIC_KEY_FALSE(switch_to_cond_stibp); > DECLARE_STATIC_KEY_FALSE(switch_mm_cond_ibpb); > DECLARE_STATIC_KEY_FALSE(switch_mm_always_ibpb); > > +DECLARE_STATIC_KEY_FALSE(vcpu_load_ibpb); How about ibpb_on_vcpu_load? To make it easy for readers to understand exactly what the knob controls.
